Polarization diverse wavelength selective switch
View Patent ↗Described herein is a wavelength selective switch (WSS) type optical switching device ( 1 ) configured for switching input optical beams from input optical fiber ports ( 3, 5 and 7 ) to an output optical fiber port ( 9 ). Device ( 1 ) includes a wavelength dispersive grism element ( 13 ) for spatially dispersing the individual wavelength channels from an input optical beam in the direction of a second axis (y-axis). The optical beams propagate from input ports ( 3, 5 and 7 ) in a forward direction and are reflected from a liquid crystal on silicon (LCOS) device ( 11 ) in a return direction to output port ( 9 ). The input optical beams are transmitted through a port selecting module ( 21 ), which provides polarization diversity to device ( 1 ) and provides capability to restrict optical beams returning from LCOS device ( 11 ) from being coupled back into input ports ( 3, 5 and 7 ).
1. An optical signal manipulation system including:
a plurality of ports that carry respective optical beams to be manipulated, each optical beam including a plurality of independent wavelength channels, the ports being divided into a first group of ports that carry a first subset of beams corresponding to a first optical device and a second group of ports that carry a second subset of beams corresponding to a second optical device;
a polarizing module for polarizing the first subset of beams into a first polarization state and for polarizing the second subset of beams into a second polarization state orthogonal to the first polarization state;
a wavelength dispersion element that spatially separates the plurality of independent wavelength channels of the first and second subsets of beams in the direction of a first dimension to produce a plurality of dispersed wavelength channels;
a separation element that spatially separates the plurality of dispersed wavelength channels of the first and second subsets of beams in the direction of a second dimension orthogonal to the first dimension; and
a processing device including a series of independent wavelength processing elements that separately process each of the dispersed wavelength channels of the first and second subsets of beams, with wavelength channels of the first subset of beams being processed independently of wavelength channels of the second subset of beams at a location spatially separated in the second dimension.
2. The system according to claim 1 further comprising a beam confining module that spatially confines the first subset of beams with the second subset of beams along a direction of propagation to a predefined spatial offset in the first dimension.
3. The system according to claim 2 wherein the beam confining module comprises a polarization beam splitter that reflects the first subset of beams and transmit the second subset of beams.
4. The system according to claim 2 wherein the beam confining module comprises a pair of spatially offset and substantially parallel reflective surfaces, a first reflective surface of the pair being positioned to reflect the first subset of beams and a second reflective surface of the pair being positioned to reflect the second subset of beams.
5. The system according to claim 1 wherein the separation element comprises a polarization beam splitter that reflects beams from the first subset of beams having the first polarization state and that transmits beams from the second subset of beams having the second polarization state.
6. The system according to claim 5 further comprising a reflective element that reflects beams from the second subset of beams onto the processing device.
7. The system according to claim 5 wherein the separation element includes a half-wave plate positioned so that it rotates the beams of the first subset of beams into the same polarization state as the beams of the second subset of beams.
8. The system according to claim 5 further comprising a birefringent wedge that angularly disperses the beams from each subset of beams prior to incidence onto the polarization beam splitter.
9. An optical switching device for processing optical beams with more than one independent wavelength channel, the device comprising:
one or more input ports for inputting optical beams in a forward direction of propagation;
a switching module that reflects beams propagating in the forward direction and that selectively switches the optical beams along predetermined paths in a return direction of propagation;
one or more output ports for receiving predetermined optical beams propagating in the return direction; and
a port selecting module for selectively directing the beams such that predetermined ones of the beams propagating in the return direction propagate along trajectories out of alignment with the input ports, the port selecting module including:
a polarization separation element that spatially separates an optical beam into two orthogonal polarization components;
a polarization rotation element that selectively rotates the polarization components with respect to each other; and
an optical power element that focuses the polarization components together in the direction of spatial separation.
10. The optical switching device according to claim 9 wherein the port selecting module includes one or more polarizing elements that polarizes the optical beams into a predetermined polarization state.
11. The optical switching device according to claim 9 wherein the polarization separation element includes a birefringent walk-off crystal element.
12. The optical switching device according to claim 9 wherein the input and output ports are disposed in an array extending in a first dimension where the spatial separation of polarization components is in a second dimension perpendicular to the first dimension.
13. The optical switching device according to claim 9 wherein the polarization rotation element includes a Faraday rotator that applies a 45° rotation to a polarization component.
14. The optical switching device according to claim 13 wherein the polarization rotation element comprises a half-wave plate element that rotates a first polarization component in a forward propagation direction and that rotate a second polarization component in a return propagation direction.
15. The optical switching device according to claim 14 wherein the first polarization component and the second polarization component are the same component.
16. The optical switching device according to claim 12 further comprising a second polarization separation element that spatially separates the two orthogonal polarization components in the first dimension.
17. The optical switching device according to claim 9 wherein the polarization rotation element is reconfigurable so as to selectivity define specific ports as being either an input port or an output port.
18. The optical switching device according to claim 17 wherein the polarization rotation element includes a transmissive liquid crystal element device including a plurality of individually drivable electro-optic cells.
19. The optical switching device according to claim 18 wherein the electro-optic cells are selectively electrically drivable between two discrete polarization rotation states, wherein one state is configured to couple an optical beam into a predetermined output port and another state is configured to couple an optical beam away from a predetermined output port.
20. The optical switching device according to claim 12 further comprising a beam shifting element that selectively applies a spatial shift to the optical beams in the first dimension based on the spatial position and polarization of the beams.
21. A wavelength manipulation device for independently manipulating optical beams from a first and second source, the optical beams having orthogonal polarizations and including a plurality of individual wavelength channels, the device comprising:
a polarizing module that polarizes optical beams from the first source into a first polarization state and that polarizes optical beams from the second source into a second polarization state orthogonal to the first state;
a wavelength dispersion element that spatially separates the plurality of wavelength channels from the optical beams in the direction of a first dimension to produce a plurality of dispersed wavelength channels;
a separation element that spatially separates the plurality of dispersed wavelength channels in the direction of a second dimension orthogonal to the first dimension;
an electrically controllable directing element that simultaneously selectively spatially directs the optical beams from both the first and second sources along predefined trajectories onto a processing device; and
the processing device including an array of independently controllable processing elements that separately and independently process the beams from the first and second sources,
wherein the electrically controllable directing element is configured to vary the predefined trajectories in response to data indicative of a local temperature of the device.
22. The device according to claim 21 wherein the electrically controllable directing element comprises a MEMS mirror.
23. The device according to claim 21 wherein the electrically controllable directing element is responsive to a detected optical reference signal.